Effect of surfactants on phosphorus release and acidogenic fermentation of waste activated sludge containing different aluminium phosphate forms.

The effects of different surfactants (rhamnolipid, trehalolipid and citrate) on phosphorus (P) release and acidogenic fermentation of waste activated sludge (WAS) containing different aluminium phosphate forms (AlPO4, Al(PO3)3) were investigated. Results showed that rhamnolipid was the most effective surfactant to release P from aluminum phosphates (AlPs)-rich sludge. Al(PO3)3 was easier to release P than AlPO4 in WAS due to their different crystal structures. Different surfactants promoted the production of different types of protein. The addition of rhamnolipid was conducive to produce propionate from WAS, while trehalolipid and citrate increased the production of n-butyrate and acetate, respectively. Citrobacter played an important role in producing phosphatase continuously for P release with rhamnolipid addition. Predictive functional profiling indicates that rhamnolipid greatly facilitated adenosine triphosphate (ATP)-binding cassette transporter and quorum sensing. These important discoveries help to enrich P recovery paths from sludge produced with Al-based coagulants in wastewater treatment plants.